Electric-circuit-control means



May 27, 1930. A. J. MAY 1,7 ,76

ELECTRIC CIRCUIT CONTROL MEANS Original Filed Nov. 20', 1925 3Shgets-Sheet l 1:15 T NEYS M ay 27, 1930., A. J. MAY 1,760,763

ELECTRIC CIRCUIT CONTROL MEANS Original Filed Noy. 20, 1925 3Sheets-Sheet 2 l l l l.

INYENTOR May 27, 1930. A. J. MAY 1,760,763

ELECTRIC CIRCUIT CONTROL MEANS I Original Filed Nov. 20, 1925 SSheets-Sheet 3 INVENT R {b/ Patented May 27, 1930 UNlTE SATES r riceADAM J". MAY, OF ROCHESTER, NEW'YOR-K, ASSIGNOE, BY MESNE ASSIGNMENTS,TO THE BITTER DENTAL IJIANUFACTURING COMPANY, INC., OF ROCHESTER, NEW

YORK, A CORPORATION GF DELAVIARE ELECTRIC-CIRCUIT-CONTROL MEANS Originalapplication filed November 20, 1925, Serial No. 70,241. Divided and thisapplication filed September 10, 1928.

The present invention relates to electric circuit control means and hasfor one object to provide improved means of this class for controllingelectric motor circuits and particularly to an improved limit switchhaving a plurality of different circuit closing positions to which it isadapted to be moved automatically by one or more parts driven by themotor such as an extensible chair section.

A further object of the invention is to provide an improved limit switchfor electric motor circuits having a plurality of different operatingpositions, the switch being under the control of an extensible chairsection for moving it to and from said positions whereby to control themovements of said chair section.

A still further object of the invention is to provide in conjunctionwith a movable chair section having a reversible motor for operating thesame and a manually controlled two-way switch, an automatic-chaircontrolled limit switch with circuit connections so arranged that thelimit switchwill have one closing position common to both closingpositions of the two-way switch and two other positions, in each ofwhich 'it is adapted to open the motor circuit with the main switch inone operating position and to close it with the main switch in anotheroperating position.

To these and other ends the invention resides in certain improvementsand combinations of parts, all as will be hereinafter more fullydescribed, the novel features being pointed out in the claims at the endof the specification.

In the drawings Figure 1 is a diagrammatic view illustrating the circuitarrangement of an A. C. and D. C. motor together with the switchestherefor in connection with a part sectional plan of the chair baseshowing the several junction boxes for the switches and a conduit forenclosing the circuit connections;

Figure 2 is a diagrammatic view in elevation illustrating a portion ofan extensible chair with the operating pins or projections for the limitswitch shown on one of the adj ustable sections;

Serial No. 134,741.

contact member in central position and illustrating one position of theswitch operating projections on the outer movable section of the chair.

Figure 8 is a similar section showing the switch after operation by thechair to one of its circuit breaking positions; and V Figure Q is asectional plan taken on line 99 of Figure 6.-

Similar reference numerals throughout the several views indicate thesame parts.

The invention disclosed herein embodies an improved electric circuitcontrol mechanism, the present application being a division of'my(to-pending application for extensible chairs filed November 20, 1925,SerialNo. 70,241.

The invention contemplates the provision of a manually controlledelectric switch and an automatic limit switch connected theretoandadapted for control bya movable part as for example, an extensible chairsection.

Referring to-the drawings, 11 represents a chair base carrying an A. C.or D. C. motor 11 adapted for connection with a suitable liftingmechanism for the chair, not shown, such as that disclosed in myco-pending application referred to above for raising and lowering theinner and outer extensible chair sections12 and 13, respectively, thelatter being guided by the base 11 and the former by the outer section13 in a well-known manner. A foot pedal 14: is provided on the base foroperating the motor reversing switch, indicated generally at 15 inFigure 1 and adapted to be disposed in a pocket or junction box 15 inthe base 11. The motor reversing switch 15 is preferably the same asthat disclosed in the application referred to above. Connected with thereversing switch is an automatic limit switch, indicated generally at 16in Figure 1 and in detail in Figures 3 to 9, inclusive, the same beingarranged for disposal in a pocket 16 and the base 11. The pockets 15 and16 are provided with cover plates 15 and 16, respectively, as shown inFigure 2. A line switch 17 is also provided, the same being adapted fordisposal in a pocket 17 in the chair base.

The A. C. and D. C. motors are indicated diagrammatically at 18 and 19,respectively. Each of the motors is preferably provided with two plugand socket connections 20 and 21, which may be combined in a singleconnection if desired. The sockets are preferably carried by the motorsand the fingers 22 which take into the sockets are adapted to projectfrom a holder 23 on the free end of a conduit 24 through which thecircuit connections extend to the junction box 15 for connection withthe switch plate 25 as shown in Figure 1. In this figure the heavy linesindicate a closed oractive circuit through the A. C. motor while thelight lines indicate, in part, the cir: cuit arrangement for the D. C.motor, certain of the wires being common to both circuits. The circuitfor the A. 0. motor is shown closed through the limit switch 16 with thelatter in the position shown in Figure 8, after it has been actuatedfrom the position shown in Figure 7 by the downward movement of thechair to approximately its lowest position.

The limit or automatic control switch 16 is adapted to be actuated byone of the adjustable sections of the chair in its up and downmovements, preferably the outer section 13, through the medium ofsuitable parts associated therewith, such as the upper and lower pins orprojections 26 and 27 respectively, in the path of which is located thecontrolling means for the limit switch which will presently bedescribed.

The limit switch embodies inner and outer switch plates 28 and 29,respectively, which are constructed of suitable insulating material andbetween which is disposed a metal plate 30, the several plates beingconnected by suitable bolts or screws 31 as shown in Figures 3 and 4.The inner plate 28 is provided with an undercut groove or recess 32 inwhich is guided a slide block 33, which is dove-tailed on its outer faceto receive the laterally projecting portion 34 of a holder 35 comprisinga plate of insulating material having on its inner face a contact bar 36secured by screws 37. The contact bar 36 is adapted for reciprocation inan elongated recess 38 formed in the plate 29 as shown in Figures 3 and4. Mounted on the inner face of the plate 29 are three fixedcontacts 39,40 and 41 which extend within the recess 38 in the path of the movablecontact 36 for engagement therewith, the latter having three differentoperating positions corresponding to different positions of the chair aswill be subsequently explained. The fixed contacts are each suitablysecured to the plate 29 as by means of the studs 42 which preferablycarry the binding posts 43 for the several wires 39 40 and 41 connectedwith said contacts as shown in Figures 1 and 3. The fixed contacts ofthe reversing switch 15 shown in Figure 1 include plugs l to 5 inclusiveadapted to take into sockets at one end of the plate 25 and also includeplugs 6 to 10 inclusive adapted to take into sockets at the opposite endof the plate. The connection 39 leads to socket for the plug 5 of theswitch plate 25 and the opposite connection 41 to socket for the plug10, each of said connections being adapted in conjunction with theconnection 40 to complete the motor circuit when the starting switch ismoved to closed position.

The slide 33 is recessed to form a housing 44 for a spring 45 having itsopposite ends engaging follower plates 46 and 47 located within andbeing free to move inwardly of the housing. The followers are each heldagainst outward movement by end closures 48 of the housing. Projectingthrough the housing and through the spring therein is an operating stem49 provided at one end with a head 50 engaging the follower 46 as shownin Figure 6. The stem is provided at its other end with lugs 51,disposed in engagement with the follower 47. The stem is recessed at itsinner end to receive a roller 52 on the outer end of a lever 53 operablewithin a slot 54 formed by cutting away a portion of the plates 28 and29 as shown in Figures '3 and 6. The lever is pivoted at 55 within thebase plate 28 and a bearing block 56 which is connected therewith byscrews 57 as shown in Figure 4. The lever is provided at its inner endwith upper, lower and intermediate projecting portions 58, 59 and 60,respectively, which terminate in the arc of a circle, the center ofwhich preferably coincides with the pivotal axis of the lever. One orthe other of these projections is at all times disposed in the path ofthe pins 26 and 27 on the movable chair section13, so that if either ofthe pins is moved past the inner end of said lever it will engage one ofthe projections and shift the movable contact 36 to make or break thecircuit as desired.

The spring housing 44 is provided at one side with three notches asindicated at 61, each of which is adapted to receive a ball 62, held infrictional engagement with the housing by a spring 63 disposed in arecess formed in the base plate 28 andsecured therein preferably by ascrew plug 64 as shown in Figure 6. Thus means is provided for resistingmovement of the housing 44;and the movable contact 36 carried therebyuntil a predetermined pressure has been built up in the spring Ell) edand the consequent burning of the contacts prevented which would not bethe case,

under slow movement of the parts. This is true regardless of thedirection of movement of the operating stem 19 and lever 53 for movingthe same.

The reversing switch includes a movable switch bar 65 having twoupstanding contacts 66 at one end and three similar contacts 67 at theother end which are suitably insulated from the contacts 66. The fixedcontact members, adapted for cooperation with the movable contacts 66are indicated, two at 68 on one side of the movable contact and two at69 on the opposite side thereof. The fixed contacts adapted forcooperation with the movable contacts 67 are indicated, three at 70 andthe other three at 71 all being shown in Figure 1. The fixed contacts 69and 71 are connected to the plugs 1 to inclusive while the fixedcontacts 68 and 70 are connected to the plugs 6 to inclusive.Movement'of the switch bar to the right or left is adapted to beeffected preferably by movement of the pedal 14 to the right or left asmay be required depending upon whether it is desired to have the motorraise or lower the chair sections. The operating means between the pedaland movable bar 65 is not shown, but is preferably the same as thatdisclosed in my co-pending application referred to above.

The fixed contacts 39 and 41 of the limit switch are connected to plugs5 and 10 of the reversing switch by wires 39 and 11 respectively asshown in Figure 1. Thewires 39 and 41 are adapted in conjunction withthe wire 40 to complete the motor circuit when the starting or reversingswitch is moved to closed position. x

As indicated in Figure 1 certain of the sockets at one side of theswitch are shown connected with certain of those at the opposite side,it beingunderstood that the arrangement is such as to afford reversal ofthe motor from either operating position, regardless of whether an A. C.or D. 0. motor is employed. With the wiring arrangement shown theseveral circuits can be easily traced for the two types of motors withthe switch in either closing position. In this connection it will beunderstood that the limit switch 16 is included in the circuit and thatwith the latter in central position as indicated in Figure 7 the motorwill become operative upon moving the starting switch to elther of its.closing positions regardless of the type of motor used. However, withthe limit switch in the position indicated in Figures 1 and 8 thecircuit through the main or starting switch can only be closed with themovable contacts of the latter adjusted to engage the fixed contacts 69and 71, the plugs 1 to 5 of which take into a series of correspondinglyarranged sockets formed in the right side of the switch plate 25, whilethe opposite plugs 6 to 10 inclusive take into a set of correspondinglyarranged sockets formed in the left side of said plate. With the limitswitch in the extreme reverse position from that shown in Figures 1 and8 the circuit willbe closed and the motor reversed when the movablecontacts of the main switch engage the fixed contacts 68 and 7 O. In thefirst named position of the switches the motor will operate to raise thechair while in the last named position it will operate to lower thesame.

In the operation of the chair, assuming it is desired to raise it fromits lowest position as indicated by the movable section 13 in Figure 8,the right side of the pedal as viewed in Figure 2 is depressed by theoperator. This operation shifts the movable contacts 66 and 67 to theright as viewed in Figure 1 and into engagement with the fixed contacts69 and T1 and closes the motor circuit through plugs 1, 2, 8, 7, 3, 4cand 5, either for the A. C. or C. motor, when it is desired to raise thechair. The motor is thus started and the lifting mechanism placed inoperation, it being understood that the limit switch at this time willbe in the position indicated in Figures 1 and 8. As the chair section 13is" moved up the pin 26 will engage theprojection 58 of the lever 53 andmove the switch to the positionshown in Figure 7 without breaking thecircuit. The operator retains his foot upon thepedal until the chair israised to the height desired and immediately upon release of the pedalthe motor circuit is broken by return of the main switch to normalinoperative position through the action or" the pedal operating spring,not shown.

In the operation just described, should the chair sections be raised tosubstantially their maximum height, the motor circuit will be Figure 7when the pedal is moved to the left to reverse the motor for the purposeof lowering the chair, it being understood that the return of the limitswitch to its intermediate position does not break the circuit. which isnow closed through the plugs 1, 6, 7, 8, 9 and 10. With the chairsection 13 in the position shown in Figure 7, the projection 60 of thelever 53 is in position to be engaged by either of the pins 26 or 27 andit will be operated by one or the other thereof, depending upon thedirection and extent of movement of the section from the position shownin said figure. The switch in this figure is in a position common toboth circuits so that should the operator depress the pedal either tothe right or left, the motor will be started.

lVhat I claim as my invention is 1. An electric switch comprising asupport having three fixed contacts thereon, a holder reciprocab'lymounted upon the support having a contact adapted for engagement withsaid fixed contacts and arranged to have three circuit closingpositions, in one of which it engages all of the fixed contacts and inany position of which itengages two of said fixed contacts,spring-pressed means adapted to resist movement of the holder to andfrom its different positions, and yieldable operating means formovingthe holder in opposite directions adapted to overcome the resistance ofsaid spring-pressed means whereby to afford a relatively quick movementof the holder to and from each of its operating positions.

2. An electric switch comprising a support having three fixed contactsthereon, a holder reciprocably mounted upon the support and providedwith a contact adapted to have three circuit closing positions, in oneof which it engages all of the fixed contacts, springpressed meansadapted to resist movement of the holder to and from its differentpositions, yieldable actuating means for moving the holder inopposite-directions adapted to overcome the resistance of said springpressed means whereby to aiford a relatively quick movement of theholder from any of its several operating positions, and a leverconnected with said actuating means and having three operating portionscorresponding to the three positions of the switch, each of saidportions being adaptedin said different switch positions to occupysubstantially a common control position from which the lever is operableback and forth between its limits of movement; V

3. An electric switch comprising a support having three fixed contactsthereon, a holder reciprocally mountedupon the support and provided witha contact adapted to have three circuit closing positions, in one ofwhich it engages all of said fixed contacts, actuating means for saidmovable contact adapted in each of its operations to effect a relativelyquick movement thereof from one position to another, and a memberoperatively associated with said actuating means and having threeoperating portions corresponding to the three positions of the switchand adapted for movement in a circular path to a common operating pointfrom which said member is operable to its different circuit controllingpositions.

4. An electric switch comprising a support, a plurality of fixedcontacts on the support, a guide upon the support, a holder slidableupon the guide, a contact movable with the holder to different circuitcontrol positions with respect to said fixed contacts, and an actuatingmember for said holder having spaced operating portions arranged tooccupy a common point in a predetermined V path upon movement of theactuating member between predetermined limits.

5. An electric switch comprising a support, a plurality of fixedcontacts thereon, a holder reciprocally mounted upon the support, acontact movable therewith to different circuit control positions withrespect to said fixed contacts, an actuating member for said holderhaving spaced operating portions arranged to occupy a common point in apredetermined path when the actuating member is moved back and forthetween predetermined limits, yieldable means for resisting back andforth movement of said holder, and spring means arranged to impart arelatively quick movement of the holder to its different controlpositions subsequent to a predetermined resistance to the movementthereof by said yieldable means.

6. An electric switch for controlling separate electric circuitscomprising a support, three fixed contacts carried by the support, aholder reciprocally mounted on the support, acontact carried by andmovable with the holder, said holder having an intermediate position inwhich its contact engages all of said fixed contacts and in whichposition the movable contact is effective to close either circuit,'saidholder being movable inv opposite direct-ions from said intermediateposition to effect independent closing of said separate circuits.

7. An electric switch for controlling separate electric circuitscomprising a support, three fixed contacts carried by the support, aholder reciprocally mounted on the support, a contact carried by andmovable with the h'older, said holder having an intermediate position inwhich its contact engages all of said fixed contacts and in whichposition the movable contact is effective to close either circuit, saidholder being movable in opposite directions from said intermediateposition to eifect independent closing of said separate circuits, springpressed means arranged to resist movement of the holder to and from eachof its circuit closing positions, and yieldable actuating means formoving the holder in opposite directions arranged to overcometheresistance of said spring pressed means, whereby to afford a relativelyquick movement ofthe holder to arate electric circuits comprising asupport, three fixed contacts carried by the support, a holderreciprocally mounted on the support, a contact carried by and movablewith the holder, said holder having an intermediate position in whichits contact engages all of said fixed contacts and in which position themovable contact is efiective to close either circuit, said holder beingmovable in opposite directions from said intermediate position to effectindependent closing of said separate circuits, and an operating memberfor said holder pivotally connected therewith having spaced actuatingportions corresponding to each circuit closing position of the movablecontact.

9. An electric switch for operation by a control device movable back andforth in a predetermined path, said switch comprising three spacedcontacts one intermediate the other two and a movable contact adapted inone circuit closing position to engage all of said contacts and arrangedin each of two other circuit closing positions to engage saidintermediate contact and one of the other of said spaced contacts, andoperating means for said movable contact having three different controlpositions corresponding to the three positions of said movable contact,said operating means extending in the path of said control device formovement thereby from each of said control positions to a differentcontrol position.

10. An electric switch for operation by a control device movable backand forth in a predetermined path, said switch comprising three spacedcontacts one intermediate the other two and a movable contact adapted inone circuit closing position to engage all of said contacts and arrangedin each of two other circuit closing positions to engage saidintermediate contact and one of the other of said spaced contacts, andan operating device for said movable contact having three spacedportions each of which is adapted to be engaged by the control devicewhen moving in opposite directions whereby to shift the movable contactto one of its circuit closing positions.

11. An electric switch for operation by a control device movable backand forth in a predetermined path and having a pair of spaced actuatingmembers for the switch, said switch comprising relatively movablecooperating switch parts for controlling different circuits and anoperating device for effecting relative movement of said parts havingthree spaced portions, one of which is adapted to be engaged foroperation by both of said actuating members in the back and forthmovement thereof and said other portions being arranged for engagementand operation each individually by one only of said spaced actuatingmembers.

ADAM J. MAY.

